Proprietary work slows progress and innovation

important insights missed by unwilling competitors
need for extra work on reporting and analysis to make use of updated processes and knowledge within the organisation - lack of transparency means inaccurate, misleading or not particularly useful reports, and a lot of work is wasted when project work is archived or disposed of, individuals’ growth not propagated to others, skills and processes and insights lost when staff move on
lose out on cross-industry or cross-discipline knowledge
for those who believe in working in public is there any responsibility/liability in regards to how particular thoughts or unfinished works are interpreted/used by others?
with particular importance in eg early stage scientific research on controversial topics
when, if ever, is it completely necessary to keep knowledge or insights or theories private? different for each of these categories? geo-politics and terrorism. weapons in the hands of your enemy. who defines enemy.
human efforts wasted on reconstructing and reverse-engineering
human efforts wasted on unneccesary or undesirable redundancy - eg redesigning under similar constraints and converging on the same idea, where steps could’ve been skipped by utilising previous work

impracticalities of using open source software

incompatibilities with other software - gap in the offerings covered by proprietary software that doesn’t play well will others
ecosystem lock-in in general
open source development is often limited by lack of maintainers or lack of funding (and therefore those who can volunteer freely)
poorly documented complex setups
generally not being well suited to collaborative work due to the above reasons/single author dogfooding bespoke setups
usually lacking in UX work/good UI
trustworthiness/non-established brand/layperson unwilling to sacrifice ease and familiarity